\documentclass{article}
\usepackage[x11names, rgb]{xcolor}
\usepackage[utf8]{inputenc}
\usepackage{tikz}
\usetikzlibrary{snakes,arrows,shapes}
\usepackage{amsmath}
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\usepackage[active,tightpage]{preview}
\PreviewEnvironment{tikzpicture}
\setlength\PreviewBorder{0pt}%
\usetikzlibrary{automata}%

\begin{document}
\pagestyle{empty}
%
%
%

\enlargethispage{100cm}
% Start of code
\begin{tikzpicture}[>=latex',join=bevel,]
\tikzstyle{every state}=[draw=blue!50,very thick,fill=blue!20]%
\node (q0) at (27bp,106bp) [state] {$\{q_{4}\}$};
  \node (q4) at (52bp,282bp) [state] {$\{q_{0}\}$};
  \node (q3) at (99bp,106bp) [state] {$\{q_{2}\}$};
  \node (q1) at (67bp,18bp) [state] {$\{q_{3}\}$};
  \node (q2) at (52bp,194bp) [state] {$\{q_{1}\}$};
  \draw [->] (q4) ..controls (52bp,252bp) and (52bp,236bp)  .. node[auto] {$\overline{a}$} (q2);
  \draw [->] (q3) ..controls (88bp,76bp) and (82bp,59bp)  .. node[auto] {$b$} (q1);
  \draw [->] (q0) ..controls (41bp,76bp) and (48bp,59bp)  .. node[auto] {$c$} (q1);
  \draw [->] (q2) ..controls (44bp,164bp) and (39bp,148bp)  .. node[auto] {$\tau$} (q0);
  \draw [->] (q2) ..controls (68bp,164bp) and (77bp,147bp)  .. node[auto] {$\tau$} (q3);
%
\end{tikzpicture}
% End of code

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\end{document}
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